The relaxation of crowd-control measures comes two years after the Smithsonian museum opened on Sept. 24, 2016. Weekend visitors will still need to have the free, timed passes, officials said.

The museum has welcomed more than 3.5 million visitors since it opened. The timed passes have been used to control crowds, limit wait times and provide for a better museum experience.

Museum officials first tested a no-pass entry on Wednesdays in April and May, and were pleased with the results, said Shrita Hernandez, the museum’s chief communications officer.

Attendance on Wednesdays in April averaged 8,550 visitors, according to the Smithsonian, significantly higher than the average Tuesday attendance that month.

“We want to test it for a longer time,” Hernandez said, “with the idea of being like other Smithsonian museums on the Mall,” which do not require passes to enter. “We want to make sure people have the easiest access to the museum as possible.”

On Wednesday, the museum began distributing free, timed passes for October, and by day’s end, passes were still available for most weekdays. In previous months, passes would be snapped up within hours. (The museum’s normal distribution day on the first Wednesday of the month was pushed back by the Fourth of July holiday, which may have led to diminished demand.)

Hernandez said the museum selected September for its month-long trial because students will be back at school and tourism will decline.

“It is traditionally not the peak season for Smithsonian institutions,” she said. “We thought it would be a good time to get some good data to see how we proceed.”

Visitors will still be required to have passes for the busy weekend days, Hernandez added.